a) Field of the Invention
The present invention relates to a miniature pump.
b) Description of the Prior Art
Out of conventional miniature pumps, a pump disclosed by Japanese Patent Kokai Publication No. Sho 62-291484 is known as a miniature pump which uses a diaphragm and has a configuration schematically shown in FIG. 1.
This conventional miniature pump uses a disk like driving plate 5 fitted over a driving shaft 4 which is fitted into a crank stand 3 fixed to an output shaft 2 of a motor 1 as shown in FIG. 1. Disposed around an outer circumferential portion of this disk like driving plate is a singularity or a plurality of cup diaphragm members 6 which have upward openings. In case of a pump in which the plurality of diaphragm members 6 are disposed, the diaphragm members are arranged at equal intervals on a circumference. Furthermore, a reference numeral 7 represents a cylindrical valve, a reference numeral 8 designates another valve, a reference numeral 9 denotes a suction port and a reference numeral 10 represents a discharge port.
The a miniature pump drives the motor 1 to rotate its output shaft 2, which rotates the crank stand 3 and causes a dish-turning-gyrating movement of the driving plate 5 by way of the driving shaft 4, thereby moving up and down driving portions 6a at roots of the diagram members 6. Accordingly, the root portion (driving portion) 6a of the cup like diaphragm member 6 which is located to a left side, for example, in FIG. 1 moves to go up from a lowered condition and the root portion (driving portion) 6a of the diaphragm member 6 which is located on a right side moves to go down from a raised condition.
By the up-down movements of the root portions of the diaphragm members 6, the diaphragm members allow a fluid to be sucked and discharged at intervals of a definite time, thereby performing a pump function.
In order to ideally reciprocate the diaphragm members 6, the above described conventional miniature pump must be configured so as to align a center G of the diaphragms 6 of the driving plate 5 with a fixed center of the output shaft. That is, the center G must be located on a prolonged line of the output shaft 2. For this reason, the driving shaft requires a bearing and the driving plate 5 is prolonged, thereby enlarging the pump as a whole.
Furthermore, since the driving portion of the diaphragm member performs a reciprocal movement per rotation of the output shaft 2, the diaphragm member 6 is abnormally deformed and a service life of the diaphragm member is extremely shortened when a rotational frequency of the motor is enhanced, that is, when the output shaft is rotated at a higher speed. A motor which is large and has strong power is therefore required.
Another conventional miniature pump is a centrifugal pump (impeller pump). This conventional centrifugal pump has a configuration, for example, shown in FIG. 2. In FIG. 2, a reference numeral 21 represents a pump chamber side case, a reference numeral 22 designates a driving side case, a reference numeral 23 denotes a partition wall for partitioning a pump chamber 24 from a driving section 25, a reference numeral 26 represents an O ring, a reference numeral 27 designates an output shaft of a motor 28, a reference numeral 29 denotes a driving side yoke plate, a reference numeral 30 represents a driving side magnet fixed to the yoke plate 29, a reference numeral 31 designates a spherical bearing, a reference numeral 32 denotes a holding section for a pump chamber side magnet and the like, a reference numeral 33 represents a pump chamber side magnet, a reference numeral 33a designates a pump chamber side yoke plate, a reference numeral 34 denotes a cover body, a reference numeral 35 represents an impeller, a reference numeral 39 designates a fluid inlet port and a reference numeral 40 denotes a fluid outlet port.
This centrifugal pump (impeller pump) drives the motor 28 to rotate the output shaft 27, which rotates the driving side magnet 30 so that the pump chamber side magnet 33 is rotated by magnetic coupling and the impeller 35 is rotated together with the pump chamber side magnet, thereby performing a pump function.
This conventional pump is used as a pump for supplying a liquid, but has defects that the pump cannot enhance a pressure or must be configured large for obtaining a high pressure and that the pump has a low efficiency. Furthermore, the pump has defects that it has a weak force to such a liquid, whereby the pump requires priming water or must be installed lower than a level of a liquid to be sucked at a start time.
Furthermore, a pump which has a configuration shown in FIG. 3 is known as a conventional example of diaphragm pump out of miniature pumps.
In FIG. 3, a reference numeral 41 represents a motor, a reference numeral 42 designates a speed reduction mechanism which consists of a gear 43 attached to an output shaft 41a of the motor 41 and a gear 44 in mesh with the gear 43, a reference numeral 45 denotes a driving shaft which is fitted and fixed into and to the gear 44 so as to be eccentric from a shaft 44a of the gear 44, a reference numeral 46 represents a connecting rod which is rotatably coupled with the driving shaft 45, and a reference numeral 47 a diaphragm which is fixed to a tip of the connecting rod 46 and made of synthetic rubber or the like. This diaphragm 47 has a sealing member 47a which is disposed on its outer circumferential portion and is sandwiched between a clamp plate 48 and a casing 49, thereby sealing a pump chamber 50 from external air. Furthermore, a reference numeral 51 represents a suction port, a reference numeral 52 designates a discharge port, and check valves 53 and 54 such as leaf valves are disposed in the suction port 51 and the discharge port 52 respectively.
When the motor 41 is driven to rotate the output shaft 41a of the motor 41 in the diaphragm pump which has the above described configuration, the gear 44 of the speed reduction mechanism 42 is rotated and the driving shaft 45 moves the diaphragm 47 up and down by way of the connecting rod 46, whereby a volume of the pump chamber 50 is increased and decreased by the up and down movements of the diaphragm 47. The leaf valve 53 is opened and a fluid is sucked through the suction port 51 when the volume of the pump chamber 50 is increased, and the leaf valve 54 is opened and the fluid is discharged through the discharge port 52 when the volume of the pump chamber 50 is decreased, whereby the diaphragm pump performs a pump function.
Since the pump shown in FIG. 3 requires a speed reduction mechanism and a crank mechanism, the pump is complicated in a structure of a driving section for performing the pump function and is large. Furthermore, the pump produces remarkable noise during operation.
Furthermore, there is known a pump which is invented by the inventor of this invention and disclosed by Japanese Patent Kokai Publication No. Hei 11-230046. This miniature pump has a configuration shown in FIG. 4.
In FIG. 4, a reference numeral 71 represents a motor, a reference numeral 72 designates an output shaft of the motor 71, a reference numeral 73 denotes a disk like rotating plate which is fixed to the output shaft 72 and has a groove 73a having an arc like sectional shape and formed along a circumference around the output shaft 72 as a center. A reference numeral 75 represents a driving plate substantially like a disk, for example, and has, like the rotating plate 73, a groove 75a which has an arc like sectional shape and formed along a circumference around a center of the driving plate 75. A ball 74 is disposed between the groove 73a of the rotating plate 73 and the groove 75a of the driving plate 75 which are formed in opposition to each other. A reference numeral 76 represents a cylinder, a reference numeral 77 designates a diaphragm which has a driving portion 77b fixed to the driving plate 75 and a reference numeral 78 denotes a valve housing (cover body): a pump chamber 82 being formed by sandwiching the diaphragm 77 between the valve housing 78 and the cylinder 76, and tightening and fixing the diaphragm 77 to the cylinder portion 76 with a screw 83, thereby sealing the diaphragm 77. Though FIG. 4 shows only one pump chamber 82 which is formed in a diaphragm portion 77c of the diaphragm, two or more diaphragm portions 77c (pump chamber 82) may be formed to compose a multi-cylinder pump.
Formed integrally with the valve housing 78 are a valve chamber 79 and a discharge port 80 communicated with the valve chamber 79, and a valve 77a which is formed integrally with the diaphragm 77 is disposed in the valve chamber 79. Furthermore, a reference numeral 84 represents a check valve and a reference numeral 85 designates a suction port.
The pump which is described above is set so that the rotation plate 73 and the driving plate 75 are raised until a center of a top surface is brought into contact with a stopper pin 76a disposed at a center of the cylinder 76 and the driving plate 75 is inclined. A stroke for a reciprocal movement of the driving portion 77b formed integrally with the diaphragm 77 is determined by an inclination angle of the driving plate 75 and the like. Furthermore, a reference numeral 90 represents a bias spring which produces appropriate friction by loading the ball when a load on the ball is light. Therefore, this bias spring 90 may not be used when appropriate friction is applied to the ball 74 in a relation to a load.
When the output shaft 72 is driven and rotated by the motor 71 in this miniature motor, the rotating plate 73 fixed to the output shaft 72 is rotated. When the rotating plate 73 is rotated, the ball 74 which is pressed to the rotating plate 75 by the bias spring 90 and the like moves around the output shaft 72 in a direction identical to a rotating direction of the rotating plate 73 while rotating. Since the groove 73a of the rotating plate 73 and the groove 75a of the driving plate 75 which have the arc like sectional shapes have radii nearly equal to each other (the radius of the groove 75a of the driving plate 75 is generally a little shorter), the ball 74 moves at a speed about half a speed of the rotating plate 73, whereby the ball 74 makes nearly one turn around the output shaft 72 when the rotating plate 73 makes two turns.
Accordingly, the ball 74 makes half a turn and moves from a location on a right side of the output shaft 72 to a location on a left side of the output shaft 72 when the rotating plate 73 makes one turn from a position shown in FIG. 4, whereby the driving plate moves the driving portion 77b of the diaphragm 77 from an upper position to a lower position. The rotation of the rotating plate 73 causes upward and downward movements of the driving portion 77b as described above, thereby performing a pump function. That is, the downward movement of the driving portion 77b from the location shown in FIG. 4 increases a volume of the pump chamber 82 and opens the valve 84, thereby allowing a fluid to flow into the pump. When the driving portion 77b goes up again, the volume of the pump chamber 82 is decreased and a gas is pressurized in the pump chamber, thereby opening the valve 77a and allows the fluid to be discharged from the discharge port 80 through the valve chamber 79.
While repeating the movements described above, the pump performs the pump function by sucking the fluid from the suction port 85 and discharging the fluid from the discharge port 80.
When the bias spring is not used, this conventional miniature pump allows the driving plate 75 to float up during driving, thereby being incapable of sufficiently transmitting the rotation of the rotating plate 73 by way of the ball 74, reciprocating the diaphragm portion at an accurate speed or at accurate time intervals, and supplying and sucking the fluid stably. Furthermore, the conventional miniature pump may produce noise since the driving plate 85 and the ball 74 are repeatedly brought into contact and separated.
In order to correct this defect, it is conceivable to dispose the bias spring 90 as shown in the conventional example as shown in FIG. 4, thereby keeping the driving plate 75 in contact with the ball 74.
When the bias spring 90 has a weak force, this method is ineffective and allows the pump to remain unchanged from the pump in which a bias spring is not used. Furthermore, the driving plate is inclined remarkably when the bias spring 90 has a strong force. A reason is that a side of the driving plate 75 to which the force of the bias spring 90 is exerted (a left side in FIG. 4) is pushed down using the ball 74 as a fulcrum as shown in FIG. 4 and a left side of the driving plate 75 in FIG. 4 is lowered, thereby enlarging an inclination angle. As a result, the driving plate 75 is apart from a tip of the stopper pin 76a, whereby a variation in inclination of the driving plate 75 is unstable, and the upward and downward movements (reciprocal movements) of the diaphragm 77 is unstable. When the bias spring 90 has a force which is further too strong, the inclination angle is further enlarged and the driving plate 75 comes into contact with the rotating plate 73, thereby posing problem that the rotation of the rotating plate 73 is unstable, that noise if further produced and the like.
The pump mentioned as the conventional example shown in FIG. 4 poses the problem when a spring has a weak force or when the spring has a strong force reversely, allows a spring force to be set appropriately only within a narrow width and operates favorably only within an extremely a narrow range of spring forces. Accordingly, the pump requires extremely high precisions for parts such as the bias spring 90, the rotating plate 73, the ball 74 and the driving plate 75, thereby requiring a high manufacturing cost.
An object of the present invention is to provide a miniature pump characterized in that the pump comprises: a pump chamber which is communicated with a suction port by way of a check valve and communicated with a discharge port by way of another check valve; a driving portion which performs a pump function by increasing and decreasing a volume of this pump chamber; a driving portion which performs the a driving portion is attached and which reciprocates the driving portion, a ball which is disposed at a location between the rotating plate and the driving plate, and apart from a rotating shaft of the rotating plate; and a spring which brings the driving plate into pressure contact with the ball by applying a force from a side of the rotating plate, an inclined direction of the driving plate is continuously changed by a movement of the ball caused due to rotation and revolution of the ball, and a pump function is performed by reciprocating the driving portion due to the change of the inclined direction of the driving plate.
Another object of the present invention is to provide a miniature pump comprising: a pump chamber which is communicated with a suction port by way of a check valve and communicated with a discharge port by way of another check valve; a driving portion which increases and decreases a volume of the pump chamber; a driving plate which reciprocates the driving portion; a rotating plate which is fixed to an output shaft of a motor; a ball which is disposed between the rotating plate and the driving plate; and a cam surface which is disposed on a rotating plate side of the driving plate, wherein the ball moves while rotating and revolving due to rotations of the rotating plate, and wherein rotations of the rotating plate causes rotations and revolution of the ball which move the ball, the movement of the ball produces a function of the cam surface which reciprocates the driving portion together with the driving plate, thereby performing a pump function.